The objective of this study is to assess changes in hospital nurse staffing, and analyze the relationship between hospital staffing and the quality of patient care over time. With the transformation of health care financing and the growth of per case and capitation payment, hospital are under strong pressure to cut length of stay and reduce inpatient days. This increases the amount of nursing needed per patient day. At the same time, pressures to control costs encourage hospitals to restrict growth in nurse staffing. It has been asserted, however, inadequate growth in staffing and shifts from RN to other nursing and non-nursing personnel place patients at greater risk of experiencing adverse outcomes or events. This study will: 1) describe changes in hospital nurse staffing over time; 2) compile a set of adverse nurse sensitive events and describe changes in the rates at which these outcomes occur over time; 3) determine whether there is a relationship between the rates of adverse nurse sensitive events and the level and mix of nursing and non-nursing personnel in hospitals; and 4) determine whether changes in nursing levels and mix are associated with increased market pressures on hospital or changes in managed care. In order to accomplish these goals, we will apply existing methods to adjust nursing staff levels to account for changes in case complexity and declining LOS. Additionally, we will develop, assess and improve methods available for measuring adverse nurse sensitive events, staffing levels and patient acuity so that staffing, adverse events and their relationship can be routinely monitored using widely available public data. This analysis will be conducted using data for 1987-1997 from state hospital discharge and hospital financial disclosure reports from California, Florida, Massachusetts, and Washington, the annual American Hospital Association survey, and data on nursing need, actual nurse staffing, and patient acuity from the Medicus Inpatient Methodologies system. Using extended longitudinal data sets will allow adequate measurement of change over time and control for hospital-specific effect.